Yarn tensioning device and arrays thereof

ABSTRACT

Yarn tensioning devices and arrays thereof which supply a multiplicity of yarns at the same tension to a weaving loom without the tendency to pull-back, roll-back or forward loop are provided for the manufacture of carpets.

INTRODUCTION

[0001] This patent application claims the benefit of priority from U.S. Provisional Patent Application Serial No. 60/452,341 which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The invention relates to a yarn tensioning device or an array of yarn tensioning devices used in the manufacture of woven tufted or looped carpets. The yarn tensioning device or arrays thereof are particularly useful in the manufacture of tufted carpets, such as the Wilton or Axminster type carpets, wherein an extra set of threads are knotted or intertwined with either the warp or weft at the fell of the cloth.

BACKGROUND OF THE INVENTION

[0003] Carpets made on a Wilton loom can show variation of pile heights and can have loop or cut tufted threads. Wilton carpets can be woven as a textured design with yarns of different color woven in digitally-controlled patterns. These patterns provide variation in color patterns as well as texture patterns since the yarns of various colors are optionally cut at the same or differing heights or alternatively looped to provide textural differentiation and to create a three-dimensional intricate pattern. The yarn is supplied at the fell of the cloth from an array of bobbins via nylon tubes of varying lengths. The multiplicity of colors and the width of the warp require extensive yarn arrays in a yarn creel. Thus, yarn for some of the tufts travels a considerably greater length than yarn in near proximity to the loom thereby creating considerably different tensions on the various yarns.

[0004] When yarn threads are unwound from their respective bobbins arrayed in a creel, yarn slips cause slacks and loops of unwound yarn to form and leads to large variation in the tension on the unwound yarn. The elasticity of the yarn combined with long traverse and the intermittent nature of the yarn travel also leads to undesired variation in yarn tension between the several threads supplied at the loom due to the increased tendency for yarn to hang at the top or bottom of the bobbin while being unwound. Increased strain in the yarn results finally in rapid slip of the yarn on the bobbin and the resulting over-run of the yarn leads to loss of tension at the point of delivery. Loose yarn can tangle with the neighboring threads thereby resulting in disruption of the tufting and weaving process.

[0005] In order for a tufting loom to operate in a stable manner it is desirable to compensate and correct for the variation in tension due to varying resistance of the several delivery paths and the stick-slip supply of yarn from distant spools on the array. As the packing of the array does not allow for uniformity of supply resistance nor sufficiently compensate for the length of travel or address the stick-slip problem of unwinding yarns having considerable elasticity, it is necessary to devise a method of ensuring that variations in tension are compensated for immediately prior to the tufting process. Conventional yarn tensioning devices have been considered for this purpose. A simple tensioning device that has hitherto been used comprises a design where yarn is drawn between two opposing spring-loaded discs. This device has critical disadvantages, however, in that it becomes less effective when fibers and dust accumulate in the constriction and in the helical spring. The accumulation of fibers and dust results in an undesirable drop of tension during use and a wide variation of the applied tension to many of the threads presented to the loom. This simple opposed disc device also occupies a considerable amount of space so that space constraints restrict its application to coarse carpets and a very limited number of tuft colors.

[0006] Another device for addressing the problem of tension control in threads moving at high speeds is disclosed in U.S. Pat. No. 2,637,511. This tension device imparts an additive pinch tension independent of the speed of travel of the thread. The device is especially useful for passage of twisted thread without run-back of the twist. A non-resilient movable shoe restrains the yarn by friction between the shoe and a non-movable reaction surface provided by a non-movable shoe. A spring-loaded lever arm has its proximal end attached to the movable shoe and to a stationary hinge at its non-proximal end. The lever is arranged in a manner which provides a reduction in pinching force if the friction force between yarn and shoe yarn increases i.e. with negative feed-back for variations in the tractive effort applied to the movable shoe. A coil spring provides a nominal pinch force when the yarn is at rest. Variations in yarn friction are thereby compensated resulting in a uniform tractive effort in order to draw the yarn forward in the weaving process. While this device provides a means of adjusting the traction and thereby the tension of yarn used for the tufting process described previously, the hinged lever arrangement occupies unnecessary space so that the device is not applicable to the manufacture of woven tufted or looped carpets of the Wilton or Axminster type.

[0007] U.S. Pat. No. 2,643,831 discloses a yarn tension device wherein thread is passed between two opposed thin strip spring members which are bowed or bent by means of a central pin connected to a spring loaded pivoted lever in order to provide friction force to the thread. The distant end of the pivoted lever has a shoe resting on the thread drawn through the device. The device thus responds to variations in yarn tension by applying a bending moment on the pair of spring members. If tension is too high the lever arm reduces the bowing of the spring members and vice versa. The sensing arm length, the spring torque applied to it and the central pin height provide adjustment of the nominal tension at the loom. The device has the ability to control the yarn tension but the components parts take up space that obviates its application as a means of controlling the multiplicity of yarns of different colors to be used in the tufting process.

[0008] U.S. Pat. No. 4,641,688 discloses a weft thread braking mechanism having a stepwise controllable braking effect. This weft thread brake is for shuttle-less weaving machines and includes two leaf springs or lamellae which rest against each other in a spring elastic manner. A thread such as the weft thread passes through a passage formed between the two leaf springs as the thread is being pulled off a supply reel or bobbin. The two leaf springs apply a braking action to the thread. In their basic position the leaf springs exert a first step of a defined braking action on the thread. Controllable members are also arranged for cooperation with the leaf spring or springs to increase or decrease the pressure of the two leaf springs toward each other. Electromagnets, compression elements, or the like, are suitable for this purpose, whereby the actuation of these control members increase the braking action even to the extent of clamping the weft thread between the leaf springs if desired.

[0009] U.S. Pat. 5,363,883 discloses a thread braking device having magnetically driven spring braking members. This thread braking device comprises a pair of braking members, which are arranged symmetrically in respect to the path of the thread. Each of the braking members has a spring member. A line-shaped, vertically arranged braking zone is defined between the spring members. For braking, the spring members are pivoted on rockers towards the thread path. Due to this movement, as well as the vertical arrangement of the spring members, the deposition of contaminations in the braking zone is avoided. The elasticity of the spring members reduces the danger of damage in the presence of thickened thread sections. This device is intended for use with fine yarns with low nominal tension.

[0010] U.S. Pat. No. 5,492,286 discloses a thread brake for the variable braking of traveling threads, wires, and the like. This brake is particularly useful for the introduction of filling thread in looms, wherein the thread passes between two brake parts which can be brought into spring application against each other. One of the brake parts forms a spring element while the other serves as an abutment. One of the brake parts is also movable in order to vary the braking. In order to improve the efficiency, it is taught that the abutment is developed as a substantially cylindrical body which is acted on rotatably by the spring element, having a first partial section which is substantially circular in cross section and a second partial section which has at least one circumferential region of reduced cross section. The abutment is seated on the shaft of an electric motor such as a stepping motor.

[0011] U.S. Pat. No. 5,655,721 disclosesa yarn tension device including a receiving plate and a pushing plate for clamping a moving yarn and a spring for urging the pushing plate toward the receiving plate. At least one of the receiving plate or the pushing plate is rotatably supported. A drive source drives the rotatable plate, and as a result the device can be maintenance-free.

[0012] However these yarn tension devices do not address the particular problem of space economy and operational reliability. Many of these applications concern yarn braking applications where yarn travel speeds are far higher than they are in the manufacture of a tufted carpet from a supply of tuft yarn. Some are exceedingly complicated and not suitable for fitting in an array where a multiplicity of yarn colors are to be made available at a pre-defined lateral position in the warp shed at the fell of cloth for knotting and subsequent cutting to form the tuft.

[0013] The present invention relates to a device directed at providing an array of yarn tensioners at each position along the warp shed where knotting is to be made and where all the available colors which may be selected for knotting in that position are made available with substantially the same yarn tension and with no danger of pull-back, roll-back or forward looping. Further, the device of the present invention provides a stable and reproducible yarn tension for an extended period without loss of efficiency due to wear, debris accumulation or yarn degradation due to excessive wear.

SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a yarn tensioning device and arrays thereof for supplying a plurality of yarn strands from a yarn creel to the needle of a tufting machine at an appropriate and uniform yarn tension while preventing interaction between the yarn strands and avoiding entanglement of the yarn strands. The devices of the present invention function in an economical and optimized manner so that a limited amount of space is required. Further, the devices are arranged in a rational and efficient manner with relation to the prior and subsequent process steps. The yarn tensioning device of the present invention comprises a frame supporting a plurality of yarn tensioning cavities and yarn braking assemblies, at least one for each yarn color that is to be woven into a single point of shed along the width of the carpet being woven. For each shed point where the tuft is to be knotted one such frame is placed so that the width of the woven carpet may be served from single frames placed at loci distributed along the complete width of the fell of cloth. The yarn is drawn through an aperture in the frame. The yarn is also prevented from pulling or rolling back so that loss of tension in the forward direction is prevented. Using this device, the knotting process can proceed under uniform conditions for each yarn thread. In a preferred embodiment, a weaving loom is equipped with an array of the yarn tensioning devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a photograph showing a loom with an array of yarn tensioning devices of the present invention.

[0016]FIG. 2 is a diagram of a single yarn tensioning device of the present invention used in the array depicted in FIG. 1.

[0017]FIGS. 3A and 3B provide diagrams of a frontal view and side view, respectively of the yarn brake assembly including the yarn holding platform.

[0018]FIG. 4 provides a close-up diagram of the spring member depicted in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention provides yarn tensioning devices and arrays of yarn tensioning devices for use in the manufacture of carpets. The yarn tensioning devices and arrays thereof are capable of supplying a plurality of yarn strands from a yarn creel to the needle of a tufting machine at an appropriate and uniform yarn tension while preventing interaction between the yarn strands and avoiding entanglement of the yarn strands. Further, the yarn tensioning devices and arrays thereof occupy a limited amount of space thus rendering them particularly useful in the manufacture of Wilton and Axminster carpets.

[0020]FIG. 1 provides a photograph showing an array of the yarn tensioning devices of the present invention being used in a loom. As can be seen in this photograph, the array of yarn tensioning devices comprises a plurality of frames, each frame supporting a plurality of yarn assembly brakes made up of yarn tensioning cavities and a braking means. One yarn tensioning cavity and brake assembly is provided for each yarn color that is to be woven into a single point of shed along the width of the carpet being woven. One frame is placed at each shed point where the tuft is to be knotted so that the width of the woven carpet may be served from a plurality of single frames placed at loci distributed along the complete width of the fell of cloth.

[0021] As shown in FIG. 2, the yarn 1 is drawn through an aperture in the frame 3. The yarn is prevented from running back by a braking force located adjacent to the aperture so that loss of tension in the forward direction is prevented. Using this device, the knotting process can proceed under uniform conditions for each yarn thread.

[0022] The yarn tensioning device comprises a frame along which are positioned a plurality of yarn brake assemblies so that a number of variously colored yarns are made available at each point of the shed of the loom where tufts may be knotted. In a preferred embodiment, as depicted in FIG. 2, six sets of yarn brake assemblies are held in position by each frame or side plate 3 of the yarn tensioning device. Elements of the yarn brake assembly are conveniently fixed in position on the frame with fasteners, such as bolts, nails, screws or other suitable means for fastening. As shown in FIG. 2, a holding bracket 2 is formed on the anterior-proximal end following the final set of yarn brake elements of the sequence.

[0023]FIGS. 3A and 3B show frontal and side views, respectively, of the yarn brake assembly including the yarn holding platform. The yarn brake assembly is formed in the rectilinear aperture and positioned along the frame. In one embodiment the yarn holding platform is a rectangular block with conical bevels on one of the narrow faces of the rectangular block which form the contact surface for the yarn to be interacted by the subsequent yarn brake element and the spring member that provides the braking force. It is preferred that the yarn holding platform is comprised of metal. FIG. 3A shows inclusion of a yarn holding platform 4 with entry and exit conical bevels 6 on one of the faces which forms the contact surface for the yarn to be interacted by the subsequent yarn brake element. The braking force of the assembly is preferably provided by a spring member 5. In a preferred embodiment the spring member 5 is comprised of a metal or metal alloy. In a further preferred embodiment the spring member 5 is comprised of steel. FIG. 3B shows a detailed view of the entry and exit conical bevels 6 on the yarn holding platform. A close-up view of the preferred spring member 5 is depicted in FIG. 4. However, as will be understood by those of skill in the art upon reading this disclosure, other braking elements can be used. Thus, the yarn braking assembly is constructed from number of apertures formed between a sequence of brake element rectilinear blocks each having a spring member on the surface positioned on the frame. The number of apertures corresponds to the number of yarn colors to be made available at each knotting position along the width of warp. Thus, a single frame such as depicted in FIG. 2 permits a multiplicity of yarn colors from a yarn creel to be supplied to the point of knotting at each lateral knotting position at a predetermined tension without being prone to retrograde movement. The yarn braking force and the ability to prevent pull-back, roll-back or forward looping of the yarns is provided by the spring member 5 retained in the aperture between successive rectilinear blocks, as depicted in FIG. 4.

[0024] The present invention thus provides a means of supplying the yarn in a relaxed manner via a yarn tensioning device or more preferably an array of yarn tensioning devices wherefrom the yarn proceeds under appropriate tension directly to each needle.

[0025] Use of this invention in the manufacture of carpets provides advantages in reliability and quality of product as yarn tension variation, the effects of debris accumulation and soiling on the brake effectiveness, and the need to repair tangles and breakages due to yarn interaction have been obviated. The advantages of the configuration are due to the manner in which brake elements are made available in restricted width so that a large number of yarn brake assemblies are mounted on a single frame and a plurality of frames can be fitted conveniently above the warp shed along the available width of the weft.

[0026] Further, the yarn tensioning device of the present invention is formed so that a plurality of frames may be laterally placed to form an array along the width of the warp without the need of displacement because of excessive space consumption. The design thus fulfills the need for a minimum of extent in the weft direction while providing the necessary number of colors to be selected for knotting at each appropriate position along the warp width.

[0027] The following nonlimiting example is provided to further illustrate the present invention.

EXAMPLE

[0028] In the photograph of FIG. 1, a 500 cm loom for tufted carpet manufacture was fitted with 1407 needles all supplied with yarn from the invention. Each yarn tensioning device had 6 brake elements for use with yarns of 6 different colors. The yarn was fetched from a yarn creel and transported in plastic tubes to the plurality of frames of yarn brakes of the array of the present invention shown in FIG. 1. The several yarns passing through each of the brake assemblies forming the array are passed on exit from the plastic tube channel through the appropriate aperture in the assembly. These threads are thereupon threaded as is usual for the operation of the loom. 

What is claimed is:
 1. A yarn tensioning device which supplies a multiplicity of yarns at the same tension and without tendency to roll-back to a loom, said yarn tensioning device comprising a frame with a sequence of apertures positioned along the frame wherein each aperture is equipped with a yarn braking assembly, said yarn braking assembly comprising a yarn holding platform with entry and exit conical bevels which forms the contact surface for the yarn and a braking element which interacts with the yarn holding platform and entry and exit bevels to control yarn tension.
 2. The yarn tensioning device of claim 1 wherein the braking element comprises a spring member.
 3. An array of yarn tensioning devices comprising a plurality of yarn tensioning devices of claim 1 laterally placed along the width of a warp of a weaving loom. 